The tube-shaped battery is used as a power source of various electronic devices such as a laptop personal computer and a digital camera. In a general tube-shaped battery, a power generating element including an electrolyte is housed in a battery can having a tube shape with a closed bottom which doubles as positive or negative electrode current collector. Needless to say, a high sealability that can surely prevent leakage of contents is required for the tube-shaped battery. In the tube-shaped battery, a configuration that seals an opening of the battery can to seal an inside of the battery can is a sealing body. The sealing body basically has a structure where an electrode terminal in a state electrically insulated is mounted on a metallic sealing plate that will be a lid of the battery-can opening.
FIG. 6 is a view illustrating a general sealing structure in a tube-shaped battery 101. FIG. 6 is a partially enlarged view of a vertical cross section of a cylindrical battery 101 cut in a planar surface including a cylinder axis 100 in which the cylindrical battery 101 is formed such that an opening 12 of a cylindrically-shaped battery can 2 that serves both as a current collector of any one of positive and negative electrodes is sealed with a sealing body 110 (hereinafter referred to as the sealing body 110 according to a conventional example). In the following, an extending direction of the cylinder axis 100 is referred to as an up-down direction, and the up and down directions are specified having the opening 12 of the battery can 2 as an upper side. The sealing body 110 according to the conventional example is configured including a circular plate-shaped metallic sealing plate (hereinafter referred to as a sealing plate 120), a terminal of the other electrode (hereinafter referred to as an electrode terminal 130), a metallic washer (hereinafter referred to as a washer 140), and a gasket 150 made of a resin having an electrical insulating property.
FIG. 7 is a perspective view of when the electrode terminal 130 is viewed from below. As illustrated in FIG. 7, the electrode terminal 130 is formed such that a column-shaped inserting portion 132 to be coaxial with a circular plate-shaped terminal portion 131 is provided to protrude to a lower surface 133 of this terminal portion 131 to extend downward. On the lower surface 133 of the terminal portion 131, a protrusion 136 whose planar shape is annular is formed to be coaxial with the inserting portion 132.
FIG. 8 is a vertical cross-sectional view of when the sealing body 110 according to the conventional example is disassembled. The sealing plate 120 is a circular plate-shape and has a circular opening 121 at the center, and the edge bends upward to form a peripheral-edge folded portion 122. The washer 140 is a simple circular plate-shape, and has a circular opening 141 in the center. The gasket 150 has a structure where circular plate parts (152a and 152b) in surface contact with each of an upper surface 123 and a lower surface 124 of the sealing plate 120 communicate with one another via a shaft portion 153 having a hollow cylindrical shape. The gasket 150 illustrated here is configured from an upper gasket 150a in surface contact with the upper surface 123 of the sealing plate 120, and a lower gasket 150b in surface contact with the lower surface 124 of the sealing plate 120. The upper gasket 150a is formed such that a circular plate portion 152a (hereinafter referred to as an upper circular plate portion 152a) having a lower surface 157a in surface contact with the upper surface 123 of the sealing plate 120, and the shaft portion 153 are integrally molded. On the upper gasket 150a, a hole 151a that penetrates from an upper surface 155a of the upper circular plate portion 152a through an inside of the shaft portion 153 to a lower end surface 156 of this shaft portion 153 is formed.
On the other hand, the lower gasket 150b has a sidewall portion 154 vertically disposed downward in the periphery of a circular plate portion 152b (hereinafter referred to as a lower circular plate portion 152b) in surface contact with the lower surface 124 of the sealing plate 120. The lower gasket 150b is integrally molded into a flat cup shape having the lower circular plate portion 152b as a bottom portion. The lower circular plate portion 152b is formed in the center with a circular opening 151b that communicates with an upper surface 157b and a lower surface 155b. 
To assemble the integral sealing body 110 using the above-described respective components (the sealing plate 120, the washer 140, the upper gasket 150a, and the lower gasket 150b) and the electrode terminal 130, first, the shaft portion 153 of the upper gasket 150a is inserted through the opening 121 of the sealing plate 120 in a fitting state, and the inserting portion 132 of the electrode terminal 130 is inserted through the hole 151a of the upper gasket 150a, the opening 151b of the lower gasket 150b, and the opening 141 of the washer 140 in order in the fitting state. Next, a part between an upper surface 134 of the electrode terminal 130 and a lower end surface 135 of the inserting portion 132 is pressed in a direction of the axis 100 to deform the inserting portion 132 in a diameter expanding direction. This crimps the respective members (the upper gasket 150a, the sealing plate 120, the lower gasket 150b, and the washer 140) between the lower surface 133 of terminal portion 131 of the electrode terminal 130 and the lower end surface 135 of the inserting portion 132. Thus, the shaft portion 153 of the upper gasket 150a is compressed between an inner surface of the opening 121 of the sealing plate 120 and an outer peripheral surface of the inserting portion 132 to fit the shaft portion 153 to the sealing plate 120. The protrusion 136 provided to protrude to the lower surface 133 of the terminal portion 131 in the electrode terminal 130 digs into the upper surface 155a of the upper gasket 150a. Thus, the integral sealing body 110 is completed. Then, the battery can 2 is sealed such that the peripheral-edge folded portion 122 of the sealing plate 120 is welded along an inner periphery of an upper end 11 of the battery can 2 by laser light beam or the like. The sealing structure of the cylindrical battery is also disclosed in, for example, Japanese Unexamined Patent Application Publication No. 2016-38991.
In the sealing body 110 according to the conventional example illustrated in FIG. 6 and FIG. 8, the column-shaped inserting portion 132 of the electrode terminal 130 has been inserted through the circular openings and holes (the opening 121, the opening 141, the hole 151a, and the opening 151b) formed on the sealing plate 120, the gasket 150, and the washer 140. The protrusion 136 formed on the lower surface 133 of terminal portion 131 in the electrode terminal 130 has the circular planar shape. Thus, when a strong force is applied to the electrode terminal 130, the column-shaped inserting portion 132 rotates around the cylinder axis 100, and there is a possibly of contact between the inserting portion 132 and the gasket 150 decreasing. When contact between the inserting portion 132 and the gasket 150 decreases, there is a possibility of leakage occurring.
For example, to directly mount the tube-shaped battery 101 on a circuit board (not illustrated), in the case where a lead tab (not illustrated) is mounted on the electrode terminal 130 by such as welding, when a strong force is applied to this lead tab from outside, this force also applies to the electrode terminal 130. The strong force may be applied to the electrode terminal 130 by such as dropping of the tube-shaped battery 101. With the sealing body 110 in the conventional tube-shaped battery 101, in such a case, there is a possibility that the contact between the inserting portion 132 and the gasket 150 decreases.
An object of the present disclosure is to provide a sealing body of a tube-shaped battery and a tube-shaped battery, in which leakage due to rotation of an electrode terminal can be prevented and sealability is further improved.